A German-language folk group famed for their alpine brass band sound and cheerful style have been faking the music on their albums for years and should give back their 13 German music awards, their former producer says.

But the manager of the seven-man Kastelruther Spatzen said it was common practice for folk music bands to use studio musicians for their albums, adding that the band from the Italian Alpine region of South Tyrol had even listed studio musicians' names on albums.

"The success of this band is based on a giant fraud," ex producer Walter Widemair told Bild newspaper, saying that only the lead singer's voice was genuine on the albums.

"The band of fakes must give back their Echo awards," he added, referring to Germany's most prestigious music award the band known for its tight leather trousers and kitschy style won 13 times.

In a statement on the website www.kastelrutherspatzen.de, manager Helmut Brossmann said Widemair had been responsible for the studio recordings for nearly 30 years and was now betraying the band for commercial reasons - to help promote his own book.

"The names of the studio musician and everyone who contributed to the chorus of songs was mentioned in every CD that they were involved in," said Brossmann. "In nearly 30 years of concert tours, they always played and sang everything live."

The dispute has captured the attention of boulevard newspapers in Germany and recalled a scandal surrounding the Milli Vanilli lip-synching duo of the early 1990s.

German producer Frank Farian turned two young Munich models, Robert Pilatus and Fabrice Morvan, into the group known as Milli Vanilli.

They won a Grammy Award in 1990 that was later stripped away when it emerged that they were only lip synching songs performed by others.